Fuel cell with metal screen flow field

Abstract

A polymer electrolyte membrane (PEM) fuel cell is provided with electrodes supplied with a reactant on each side of a catalyzed membrane assembly (CMA). The fuel cell includes a metal mesh defining a rectangular flow-field pattern having an inlet at a first corner and an outlet at a second corner located on a diagonal from the first corner, wherein all flow paths from the inlet to the outlet through the square flow field pattern are equivalent to uniformly distribute the reactant over the CMA. In a preferred form of metal mesh, a square weave screen forms the flow-field pattern. In a particular characterization of the present invention, a bipolar plate electrically connects adjacent fuel cells, where the bipolar plate includes a thin metal foil having an anode side and a cathode side; a first metal mesh on the anode side of the thin metal foil; and a second metal mesh on the cathode side of the thin metal foil. In another characterization of the present invention, a cooling plate assembly cools adjacent fuel cells, where the cooling plate assembly includes an anode electrode and a cathode electrode formed of thin conducting foils; and a metal mesh flow field therebetween for distributing cooling water flow over the electrodes to remove heat generated by the fuel cells.

What is claimed is: 
     
       1. In a PEM fuel cell stack, a bipolar plate for electrically connecting adjacent fuel cells, said bipolar plate comprising: a thin metal foil having an anode side and a cathode side;   a first metal mesh on said anode side of said thin metal foil; and   a second metal mesh on said cathode side of said thin metal foil.   
     
     
       2. A bipolar plate according to claim 1, wherein said thin metal foil has a thickness less than about 0.508 mm/0.020 in. 
     
     
       3. A bipolar plate according to claim 2, wherein said thin metal foil has a thickness of about 0.254 mm/0.010 inc.